package com.hmdp.service.impl;

import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.dto.Result;
import com.hmdp.entity.Blog;
import com.hmdp.entity.Shop;
import com.hmdp.mapper.ShopMapper;
import com.hmdp.service.IShopService;
import com.hmdp.utils.CacheClient;
import com.hmdp.utils.RedisConstants;
import com.hmdp.utils.RedisData;
import com.hmdp.utils.SystemConstants;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.geo.Distance;
import org.springframework.data.geo.GeoResult;
import org.springframework.data.geo.GeoResults;
import org.springframework.data.redis.connection.RedisGeoCommands;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.domain.geo.GeoReference;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.Resource;
import java.time.LocalDateTime;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

import static com.hmdp.utils.RedisConstants.CACHE_SHOP_TTL;
import static com.hmdp.utils.RedisConstants.SHOP_GEO_KEY;

/**
 * <p>
 *  服务实现类
 * </p>
 * @author amanda
 * @since 2021-12-22
 */
@Service
public class ShopServiceImpl extends ServiceImpl<ShopMapper, Shop> implements IShopService {
    @Autowired
    private StringRedisTemplate stringRedisTemplate;
    @Resource
    private CacheClient cacheClient;
    @Override
    public Result queryById(Long id) {
        // 缓存穿透
        //Shop shop = queryWithPassThrough(id);
        Shop shop = cacheClient.getWithPassThrough(RedisConstants.CACHE_SHOP_KEY,id,
                Shop.class,this::getById,CACHE_SHOP_TTL,TimeUnit.MINUTES);
        // 互斥解决缓存击穿
        //Shop shop = queryWithMutex(id);
        // 逻辑过期解决缓存击穿
        //Shop shop = queryWithLoginExpire(id);
        if (shop == null) {
            return Result.fail("店铺不存在！");
        }
        return Result.ok(shop);
    }
    private static final ExecutorService CACHE_REBUILD_EXECUTOR = Executors.newFixedThreadPool(10);
    /**
     * 逻辑过期解决缓存击穿
     * @param id
     * @return
     */
    public Shop queryWithLoginExpire(Long id) {
        String key = RedisConstants.CACHE_SHOP_KEY + id;
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        if (StrUtil.isBlank(shopJson)) {
            return null;
        }
        // 命中，先把json反序列化为对象
        RedisData redisData = JSONUtil.toBean(shopJson, RedisData.class);
        Shop shop = JSONUtil.toBean((JSONObject) redisData.getData(), Shop.class);
        LocalDateTime expireTime = redisData.getExpireTime();
        // 判断是否过期
        if(expireTime.isAfter(LocalDateTime.now())) {
            // 未过期，直接返回
            return shop;
        }
        // 过期。缓存重建
        // 获取互斥锁
        String lockKey = RedisConstants.LOCK_SHOP_KEY+id;
        Boolean aBoolean = tryLock(lockKey);
        // 判断是否获取锁成功
        if (aBoolean) {
            // 成功，开启独立线程
            CACHE_REBUILD_EXECUTOR.submit(()->{
                try {
                    this.saveShop2Redis(id,20L);
                } catch (Exception e) {
                    throw new RuntimeException(e);
                }finally {
                    tryDisLock(lockKey);
                }
            });
        }
        // 返回信息
        return shop;
    }
    /**
     * 互斥解决缓存击穿
     * @param id
     * @return
     */
    public Shop queryWithMutex(Long id) {
        String key = RedisConstants.CACHE_SHOP_KEY + id;
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        if (StrUtil.isNotBlank(shopJson)) {
            return JSONUtil.toBean(shopJson, Shop.class);
        }
        if (shopJson != null) {
            return null;
        }
        // 获取互斥锁
        String lockKey = "lock:shop:"+id;
        Shop shop = null;
        try {
            Boolean aBoolean = tryLock(lockKey);
            // 判断是否获取成功
            if (!aBoolean) {
                // 失败，休眠等待
                Thread.sleep(50);
                queryWithMutex(id);
            }
            // 成功，查询数据库
            shop = getById(id);
            // 模拟重建的延时
            //Thread.sleep(200);
            if (shop == null) {
                stringRedisTemplate.opsForValue().set(key,"",RedisConstants.CACHE_NULL_TTL,TimeUnit.MINUTES);
                return null;
            }
            stringRedisTemplate.opsForValue().set(key,JSONUtil.toJsonStr(shop),
                    CACHE_SHOP_TTL,TimeUnit.MINUTES);
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        }finally {
            // 释放互斥锁
            tryDisLock(lockKey);
        }
        return shop;
    }
    /**
     * 缓存穿透
     * @param id
     * @return
     */
    /*public Shop queryWithPassThrough(Long id) {
        // 从redis查询缓存
        String key = RedisConstants.CACHE_SHOP_KEY + id;
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        // 判断是否存在
        if (StrUtil.isNotBlank(shopJson)) {
            // 存在直接返回
            return JSONUtil.toBean(shopJson, Shop.class);
        }
        if (shopJson != null) {
            return null;
        }
        // 不存在则查询数据库
        Shop shop = getById(id);
        // 数据库中不存在信息，返回错误
        if (shop == null) {
            stringRedisTemplate.opsForValue().set(key,"",RedisConstants.CACHE_NULL_TTL,TimeUnit.MINUTES);
            return null;
        }
        // 数据库存在信息，写入redis返回
        stringRedisTemplate.opsForValue().set(key,JSONUtil.toJsonStr(shop),
                RedisConstants.CACHE_SHOP_TTL,TimeUnit.MINUTES);
        return shop;
    }*/
    /**
     * 获取互斥锁
     * @param key
     * @return
     */
    private Boolean tryLock(String key) {
        Boolean aBoolean = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", 10, TimeUnit.SECONDS);
        return BooleanUtil.isTrue(aBoolean);
    }
    /**
     * 释放锁
     * @param key
     */
    private void tryDisLock(String key) {
        stringRedisTemplate.delete(key);
    }

    public void saveShop2Redis(Long id,Long expireSeconds) throws InterruptedException{
        // 查询数据库
        Shop shop = getById(id);
        // 封装逻辑过期时间
        RedisData redisData = new RedisData();
        redisData.setData(shop);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(expireSeconds));
        // 写入redis
        stringRedisTemplate.opsForValue().set(RedisConstants.CACHE_SHOP_KEY+id,JSONUtil.toJsonStr(redisData));
    }
    @Override
    @Transactional
    public Result update(Shop shop) {
        Long id = shop.getId();
        if (id == null) {
            return Result.fail("店铺id不能为空");
        }
        // 更新数据库
        updateById(shop);
        // 删除缓存
        stringRedisTemplate.delete(RedisConstants.CACHE_SHOP_KEY + shop.getId());
        return Result.ok();
    }

    @Override
    public Result queryShopByType(Integer typeId, Integer current, Double x, Double y) {
        // 1.判断是否需要根据坐标查询
        if (x == null || y == null) {
            // 直接查询数据库
            Page<Shop> page = query().eq("type_id", typeId)
                    .page(new Page<>(current, SystemConstants.DEFAULT_PAGE_SIZE));
            // 返回数据
            return Result.ok(page.getRecords());
        }
        // 2.计算分页参数
        int from = (current - 1) * DEFAULT_BATCH_SIZE;
        int end = current * DEFAULT_BATCH_SIZE;
        // 3.查询redis、按照距离排序、分页。结果：shopId、distance
        String key = SHOP_GEO_KEY + typeId;
        // GEOSEARCH key BYLONLAT x y BYRADIUS 10 WITHDISTANCE
        GeoResults<RedisGeoCommands.GeoLocation<String>> results = stringRedisTemplate.opsForGeo()
                .search(key,
                        GeoReference.fromCoordinate(x, y),
                        new Distance(5000),
                        RedisGeoCommands.GeoSearchCommandArgs.newGeoSearchArgs().includeDistance().limit(end)
                );
        // 4.解析出id
        if (results == null) {
            return Result.ok(Collections.emptyList());
        }
        List<GeoResult<RedisGeoCommands.GeoLocation<String>>> list = results.getContent();
        if(list.size() < from) {
            // 没有下一页，结束
            return Result.ok(Collections.emptyList());
        }
        // 4.1 截取 from-end 的部分
        List<Long> ids = new ArrayList<>(list.size());
        HashMap<String, Distance> distanceMap = new HashMap<>(list.size());
        list.stream().skip(from).forEach(result -> {
            // 4.2 获取店铺id
            String shopIdStr = result.getContent().getName();
            ids.add(Long.valueOf(shopIdStr));
            // 4.3 获取距离
            Distance distance = result.getDistance();
            distanceMap.put(shopIdStr,distance);
        });
        // 5.根据id查询时候shop
        String idStr = StrUtil.join(",", ids);
        List<Shop> shops = query().in("id", ids)
                .last("ORDER BY FIELD(id," + idStr + ")")
                .list();
        for (Shop shop : shops) {
            shop.setDistance(distanceMap.get(shop.getId().toString()).getValue());
        }
        // 6.返回
        return Result.ok(shops);
    }
}
